The use of bone screw anchors to hold sutures is a widely accepted practice in shoulder or knee repair and fixation of soft tissue such as ligaments, cartilage and tendons to bone. Ideally the suture anchor is easy to install and provides a solid reliable way to fix the sutures to the bone. The bone has a hard outer cortical shell with a softer underlying region of cancellous bone tissue. The anchor must hold sutures after thousands of repetitive motions tensioning and relaxation until the ligament or tendon repair has time to heal and secure itself to the bone and muscle tissue.
Older style bone anchors had an external eyelet to allow the sutures to be fed through after the screw was driven into the bone. This left the eyelet exposed in the soft muscle tissue.
Later versions of bone anchors have the sutures inserted inside the screw tip well inside the bone. This allows the screw outer end to stay flush with the cortical bone outer surface. The sutures can pass inside in some hollow screws from the tip to the outer surface. Others have the sutures held at the tip end and are exterior held between the anchor screw threads and the bone. In some suture anchor systems there is a self-driving feature that has a stainless steel punch with a steel tip that can be malleted into the bone. This design leaves the tip end trapped in the bone opening meaning the patient has a small steel tip in his shoulder or knee.
Ideally the procedure should insure the bone anchor is easily installed leaving no punch tip fragments in the body and more particularly avoiding having steel tips or metal fragments left in the bone.
The present invention provides a threaded bone anchor that is easy to install wherein the sutures are held without leaving metal fragments or metal tips and, furthermore, this is accomplished with a unique insertion tool and anchor screw assembly to make the procedure simple and convenient to use.